1. Field of the Invention
This invention relates to generally to integrated circuits and, more particularly, to the conducting metal strips that electrically interconnect the components in the circuit. Typically, these metal strips are arranged in layers, typically called metal layers. An integrated circuit may have a plurality of metal layers.
2. Description of the Related Art
As the scale of integrated circuits has decreased, the distance between conducting strips electrically coupling components in the integrated circuit has necessarily decreased. The decreased spacing between conducting paths has increased the cross-talk between the conducting paths and has increased the capacitance. The increased cross-talk provides for a possible compromise of the integrity of the signals transmitted on the conducting path and the increased capacitance has compromised the speed with which signals can be transmitted over the conducting path. In the past, attempts have been made to decrease the dielectric constant between the conducting paths. A decrease in the dielectric constant results in both decreased cross-talk and decreased capacitance, thereby increasing the performance of the integrated circuit. However, the decrease the dielectric constant with materials compatible with integrated circuit technology, while improving the performance of the integrated circuits, never-the-less further improvement of the performance of integrated circuit is required.
A need has therefore been felt for a technique to decrease the dielectric constant of the material between the conducting strips of a metal layer.
The aforementioned and other features are accomplished, according to the present invention, by introducing a gas (typically air) into the region between the conducting strips of a metal layer, the gas having a lower dielectric constant than materials compatible with the processes for manufacturing integrated circuits. After formation of conducting strips of the metal layer material, a thin protective dielectric film is placed over the metal layer material and the exposed dielectric material upon which the metal layer conducting strips are formed. A fill layer material and an oxide cap material are formed over the remaining metal layer material and the exposed dielectric layer. The vias are formed in the fill material and the oxide cap material.
These and other features of the present invention will be understood upon the reading of the following description in conjunction with the Figures.